Since he knows everything about us, is it only fair that we get to know him?

As of three years ago Facebookwas capable of collecting 600 trillion bytes of information each day and storing it in a data warehouse capable of holding 300 quadrillion bytes. But however much data the social-media giant is now collecting on its two billion active monthly users, it’s evidently not enough for founder and CEO Mark Zuckerberg. So he’s opted for a rather less efficient method of gathering information. The Journal’s Reid Epstein and Deepa Seetharaman report:

Mark Zuckerberg is trying to understand America, so he’s embarked on a journey to meet people like hockey moms and steelworkers who don’t...